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10.Hystrix断路器

2022-06-28 16:09:00 【苦 糖 果】

学习B站尚硅谷周阳老师SpringCloud的听课笔记

1. 概述

1.1分布式系统面临的问题

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1.2.是什么

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1.3.能干嘛

服务降级
服务熔断
服务限流
接近实时的监控

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github地址：https://github.com/Netflix/Hystrix/wiki/How-To-Use

Hystrix官宣，停更进维 ，被动修复bugs，不再接受合并请求，不再发布新版本

2.hystrix案例

2.1 新建cloud-provider-hystrix-payment8001

2.1.1 改pom
<dependencies>
        <!--新增hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
2.1.2改yml
server:
  port: 8001

eureka:
  client:
    register-with-eureka: true    #表识不向注册中心注册自己
    fetch-registry: true   #表示自己就是注册中心，职责是维护服务实例，并不需要去检索服务
    service-url:
      # defaultZone: http://eureka7002.com:7002/eureka/ #设置与eureka server交互的地址查询服务和注册服务都需要依赖这个地址
      defaultZone: http://eureka7001.com:7001/eureka/
# server:
# enable-self-preservation: false
spring:
  application:
    name: cloud-provider-hystrix-payment
# eviction-interval-timer-in-ms: 2000
2.1.3主启动类与业务类
@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixMain8001 {
    
    public static void main(String[] args) {
    
        SpringApplication.run(PaymentHystrixMain8001.class,args);
    }
}

@RestController
@Slf4j
public class PaymentController {
    

    @Resource
    private PaymentService paymentService;

    @Value("${server.port}")
    private String serverPort;

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
    
        String result = paymentService.paymentInfo_OK(id);
        log.info("*******result:"+result);
        return result;
    }
    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
    
        String result = paymentService.paymentInfo_TimeOut(id);
        log.info("*******result:"+result);
        return result;
    }
}

@Service
public class PaymentService {
    

    //成功
    public String paymentInfo_OK(Integer id){
    
        return "线程池："+Thread.currentThread().getName()+" paymentInfo_OK,id： "+id+"\t"+"哈哈哈"  ;
    }

    //失败
    public String paymentInfo_TimeOut(Integer id){
    
        int timeNumber = 3;
        try {
     TimeUnit.SECONDS.sleep(timeNumber); }catch (Exception e) {
    e.printStackTrace();}
        return "线程池："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+"呜呜呜"+" 耗时(秒)"+timeNumber;
    }
}
2.1.4正常测试

启动eureka7001，启动cloud-provider-hystrix-payment8001

访问：http://localhost:8001/payment/hystrix/ok/31 和 http://localhost:8001/payment/hystrix/timeout/31

2.1.5 高并发测试

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结果：ok和timeout这两个接口都在转圈圈

why?只是压测timeout接口，ok接口为何会变慢？

tomcat的默认的工作线程数被打满了，没有多余的线程来分解压力和处理。

2.2.cloud-consumer-feign-hystrix-order80

2.2.1改pom
<dependencies>
        <!--新增hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
2.2.2改yml
server
  port: 80

eureka:
  client:
    register-with-eureka: true    #表识不向注册中心注册自己
    fetch-registry: true   #表示自己就是注册中心，职责是维护服务实例，并不需要去检索服务
    service-url:
             defaultZone: http://eureka7001.com:7001/eureka/

spring:
  application:
    name: cloud-provider-hystrix-order
2.2.3主启动类与业务类
@SpringBootApplication
@EnableFeignClients
public class OrderHystrixMain80 {
    
    public static void main(String[] args) {
    
        SpringApplication.run(OrderHystrixMain80.class,args);
    }
}

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT")
public interface PaymentHystrixService {
    
    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);

    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
}

@RestController
@Slf4j
public class OrderHystrixController {
    

    @Resource
    private PaymentHystrixService paymentHystrixService;

    @Value("${server.port}")
    private String serverPort;

    @GetMapping("/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
    
        String result = paymentHystrixService.paymentInfo_OK(id);
        log.info("*******result:"+result);
        return result;
    }
    @GetMapping("/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
    
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        log.info("*******result:"+result);
        return result;
    }
2.2.4测试

http://localhost/consumer/payment/hystrix/ok/31 和 http://localhost/consumer/payment/hystrix/timeout/31

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2. 3服务降级

服务降级可以做在服务端，也可以做在客户端。

2.3.1服务端8001服务降级

主启动类添加注解：@EnableHystrix，具体方法添加@HystrixCommand

设置自身调用超时时间的峰值，峰值内可以正常运行，超过了需要有兜底的方法处理，作服务降级fallback

一旦调用服务方法失败并抛出了错误信息后，会自动调用@HystrixCommand标注好的fallbackMethod调用类中的指定方法

@Service
public class PaymentService {
    

    //成功
    public String paymentInfo_OK(Integer id){
    
        return "线程池："+Thread.currentThread().getName()+" paymentInfo_OK,id： "+id+"\t"+"哈哈哈"  ;
    }

    //失败
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
    
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")  //3秒钟以内就是正常的业务逻辑
    })
    public String paymentInfo_TimeOut(Integer id){
    
       // int timeNumber = 5;
        int age = 10/0;
       // try { TimeUnit.SECONDS.sleep(timeNumber); }catch (Exception e) {e.printStackTrace();}
        //return "线程池："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+"呜呜呜"+" 耗时(秒)"+timeNumber;
        return "线程池："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+"呜呜呜"+" 耗时(秒)";
    }

    //兜底方法
    public String paymentInfo_TimeOutHandler(Integer id){
    
        return "线程池："+Thread.currentThread().getName()+" 系统繁忙, 请稍候再试 ,id： "+id+"\t"+"哭了哇呜";
    }

}

在这里插入图片描述

2.3.2客户端80服务降级

80订单微服务，也可以更好的保护自己，自己也依样画葫芦进行客户端降级保护

feign:
  hystrix:
    enabled: true #如果处理自身的容错就开启。开启方式与生产端不一样

主启动类添加注解：@EnableHystrix，具体方法添加@HystrixCommand

当前问题：和业务逻辑混一起？？？混乱

根据cloud-consumer-feign-hystrix-order80已经有的PaymentHystrixService接口，重新新建一个类（PaymentFallbackService）实现该接口，统一为接口里面的方法进行异常处理

@Component
public class PaymentFallbackService implements PaymentHystrixService {
    
    @Override
    public String paymentInfo_OK(Integer id) {
    
        return "-----PaymentFallbackService fall back-paymentInfo_OK , (┬＿┬)";
    }

    @Override
    public String paymentInfo_TimeOut(Integer id) {
    
        return "-----PaymentFallbackService fall back-paymentInfo_TimeOut , (┬＿┬)";
    }
}

在PaymentHystrixService 中注明fallback的类为PaymentFallbackService

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT",fallback = PaymentFallbackService.class)
public interface PaymentHystrixService {
    

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);

    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);

}
2.3.3 测试

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总结：
在客户端和服务端同是配置了服务降级的情况下，如果是客户端设置超时时间在服务端看来是正常情况，则会走客户端的降级逻辑。反之，则走服务端降级逻辑。
如果服务端出现运行时异常，则会走服务端降级逻辑。
如果服务端宕机，则会走客户端降级逻辑。

原网站

版权声明
本文为[苦 糖 果]所创，转载请带上原文链接，感谢
https://blog.csdn.net/qq_44300280/article/details/125491599

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